Four hundred and fourteen adoptees were located in a population of 28,879 males born within a 4-year period. For all of these males, two social class ratings were obtained, based upon their occupations at age 25–28 and 35–38. A single rating was obtained for their fathers, based upon occupation at the time of birth of the population males. In the case of adoptees, this rating was obtained for both the biological and the adoptive fathers. The adoptees had, at both ages, an average social class not deviating from that of the population at large. Their biological fathers were, however, below average paternal social class and their adoptive fathers were above it. Positive correlations for social class were found between the adoptees, at both ages, and their biological and adoptive fathers. The social class of adoptees is less well predicted by that of their biological and adoptive fathers, even when these are taken jointly, than the social class of sons in the population is predicted by that of their fathers. Evidence from both the group means and the correlations suggests that the adoptees at age 35–38 came to resemble their biological fathers in social class more than they had done at age 25–28.